Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque

H,W=map(int,input().split())
s=[]

cnt=0
for i in range(H):
    temp=list(input())
    cnt+=temp.count(".")
    s.append(temp)

d=deque([[0,0]])
c=[[10000]*W for i in range(H)]
step=[[-1,0],[0,-1],[1,0],[0,1]]
c[0][0]=1

while d:
    h0,w0=d.popleft()
    for h1,w1 in step:
        h = h0 + h1
        w = w0 + w1
        if h<0 or h>=H or w<0 or w>=W or s[h][w]=="#" or c[h][w]!=10000:
            continue
        if h==H-1 and w==W-1:
            ans = cnt - c[h0][w0]-1
            print(ans)
            exit()
        c[h][w]=c[h0][w0]+1
        d.append([h,w])
print(-1)